I just did a test with smbclient and I get different incorrect behaviour. On my server I have 65 directories in the "pix" share whose names start with "2004". When I use smbclient to attach, do an 'ls' and look at the results, I only see 34 of them. If I do 'ls 2004_08*' I see all 23 directories that start with that prefix.
I can attach some strace output if that would be helpful.